Earth retention systems provide shoring for excavation support and reinforcement for the permanent stabilization of deep cuts and slopes. Soil nailing supports excavations and provides slope stability control. Deep foundations transfer building loads to a subsurface layer of the earth beneath the surface.
Soil nailing is a construction technique that inserts reinforcing bars (rebar), which may be high-strength steel bar or steel strand tendon, into a drilled shaft/bore hole to provide permanent or temporary support to unstable or potentially unstable slopes. Soil nailing may be used, for example, to stabilize slopes and landslides, provide earth retention for excavations, and repair existing retaining walls. A type of deep foundation is created by drilling a hole/shaft into the earth to bedrock and filling the hole/shaft with a single rod of rebar. The drilled shaft/bore hole is then filled with grout or concrete to affix the rebar in place.
Without proper alignment of the rebar within the drilled shaft/bore hole, the rebar cannot perform the function for which it was designed or may become compromised over time due to corrosion and/or misalignment. Because the rebar is surrounded by grout or concrete, the position of the rebar within the drilled shaft/bore hole cannot be inspected after the grout has been placed within the drilled shaft/bore hole.
U.S. Pat. No. 6,299,386 discloses a method and apparatus for shoring a wall. The method includes inserting retaining elements substantially vertically and side by side into an earthen mass to shore the face of an excavation. Soil nails are then inserted into the excavation plane, at the approximate midpoint between a pair of adjacent retaining elements. The soil nails include a threaded core element that receives at least two centralizers. An exposed tip portion of each soil nail attaches to a wall, which is a substantially horizontal element that contacts a retaining element on both sides of each soil nail. The concrete reinforcement bars can then receive a concrete fill to form a solid wale structure. Face stability is achieved with the pre-installed retaining elements, which with the wales provide complete facing support.
A rebar centralizer is disclosed in U.S. Patent Publ. No. 2015/0284958. In this document, a rebar centralizer system comprises a first ring and a second ring configured to be positioned in an angular relationship with each other. The first and second rings are configured to at least partially intersect so as to present at least one interior corner in which a section of rebar can be secured.
U.S. Pat. No. 5,542,785 discloses a rebar cage wheel spacer centralizer system for drilled shafts. In this document, a spacer is mounted on a lateral rebar tie of a reinforcement cage of a poured concrete foundation support. The spacer includes a pair of interlocking wheel members which lock the wheel members together in a mated interlocked relationship rotatably mounted about a lateral tie of the reinforcement cage to form the spacer. Each spacer is formed from a pair of substantially identical substantially semi-cylindrically shaped interlocking wheel members which, when assembled, form rotatable wheel assemblies. As the reinforcement cage is inserted into an excavated shaft, the outer side wall of the spacer engages and rolls along the side wall thereof. The engagement of the side wall of the excavated shaft by the spacers centers the reinforcement cage within the excavated shaft and maintains the reinforcement cage in its centered position as the excavated shaft is filled with concrete.